After that, U’va L’Tzion, also named “Kedushah d’Sidra,” is recited. It contains the verses “Kadosh, Kadosh, Kadosh,” “Baruch kevod Hashem mimkomo,” and “Hashem yimloch l’olam va’ed,” with their translation into Aramaic. Chazal instituted its recital so that every person praying would merit learning some verses of the Prophets (Nevi’im) every day. That is why the verses are translated into Aramaic, so that the whole nation, which was fluent in Aramaic at that time, would understand their meaning. The Chachamim highly praise the recital of Kedushah d’Sidra, for after the destruction of the Temple, it became one of the remaining practices in whose merit the world stands (Sotah 49a). Rashi explains that its recital possesses two virtues: the virtue of Torah learning, and that the verses discuss Hashem’s holiness. In Shacharit of Shabbat, there is no need to say Kedushah d’Sidra, for one’s obligation to learn the Prophets is already fulfilled by reading the Haftarah. Nevertheless, to avoid cancelling its recital altogether, it became customary to recite it before Minchah, thereby adding some extra learning on Shabbat, particularly learning that pertaining to the sanctity of Hashem.
Some say that the Chachamim established the recital of Kedushah d’Sidra when hostile rulers decreed upon Israel not to recite Kedushah, and persecutors would stand guard at the prayer services until after the Amidah repetition. After the guards left, the minyan would recite Kedushah d’Sidra. Even after the decree was abolished, the custom to recite Kedushah d’Sidra endured (Shibolei Haleket 44; Beit Yosef 132:2).
Hence, Kedushah is recited three times in Shacharit: first in Birkat Yotzer HaMeorot, again in the Amidah repetition, and a third time in Kedushah d’Sidra. Similarly, we find that many important prayers were established to be recited three times, such as Tehillah L’David (Ashrei) every day, and Vayechulu on Erev Shabbat.
In Kedushah, the congregation recites the verses “Kadosh” and “Baruch” in unison. This is true in Kedushah d’Sidra as well, and for that reason, the chazan must recite the introductory verse preceding Kedushah out loud. It is best that a person praying individually recites these verses in the tune of Torah reading with cantillation signs. This is in keeping with the opinion that, because it is a matter of sanctity, it necessitates a minyan, but when it is recited in cantillation, it resembles reading from the Torah and thus there is no need for a minyan. Someone who does not know how to recite the verses with the cantillation signs may recite Kedushah d’Sidra without them, for according to the halachah, an individual praying may also recite Kedushah d’Sidra since the verses only relay how the angels sanctify the Blessed One’s Name.
As a continuation of Kedushah d’Sidra, the Geonim were accustomed to reciting additional verses and requests concerning atonement, faith, and Torah. Some recited the entire wording that is before us today (the Siddur of Rav Amram Gaon), and others recited a slightly shorter wording (the Siddur of the Rasag). During the time of the Rishonim, everyone became accustomed to reciting the full wording that we have today, with slight differences between the ethnic groups.
After Kedushah d’Sidra, the chazan recites Kaddish-Titkabal in which, in addition from the main part of the Kaddish, we request that our prayers be accepted. Therefore, the chazan must be careful not to talk from the Amidah repetition until after this Kaddish.
. The Rishonim are also divided concerning Kedushah in Birkat Yotzer HaMeorot, and even in that case the majority of poskim maintain that an individual is permitted to recite it. Yet, in order to fulfill one’s obligation according to all opinions, it is best to recite it with cantillation signs, as implied from the Shulchan Aruch and Rama, Orach Chaim 59:3. Regarding Kedushah d’Sidra, according to more poskim, an individual may recite it. See Yabia Omer, part 5, 7:2.
There are those who prefer to recite Kedushah d’Sidra while standing, as one does for the Kedushah of the Amidah repetition. However, the minhag is to recite it while sitting, which is the minhag of the kabbalists, and hence, it can be understood that this Kedushah does not require a minyan.
The Mishnah Berurah 132:3 writes that an individual who did not yet finish Lamenatze’ach or Ashrei when the congregation already arrived at the verses of Kedushah should skip ahead in order to say those verses with the minyan. Kaf HaChaim writes that he should not skip, for it is more important to recite the prayers in their correct order. The Mishnah Berurah 132:4 writes that the translation of the verses into Aramaic must be recited quietly. Sha’arei Teshuvah writes that the Ari was not strict concerning this.